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- 2015 (14) (entfernen)
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- Injury (14) (entfernen)
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This study aimed at developing an injury estimation algorithm for AACN technologies for Germany and compared them to findings based on Japanese data. The data to build and to verify the algorithm was obtained from the German in-depth Accident Database (GIDAS) and split into a training and a validation dataset. Significant input variables and the generalized linear regression model to predict severe injuries (ISS>15) were selected to maximize area under the receiver operating characteristic curve (AUC). Probit regression with the input parameter multiple impact, delta v, seatbelt use and impact direction gave the largest AUC of 0.91. Sensitivity of the algorithm was validated at 90% and specificity at 76% for an injury risk threshold of 2%. It appears that no major differences between Japan and Germany exist for injury estimation based on delta v and impact direction. However, far side impact and multiple crash events appear to be associated with a larger risk increase in the German data.
Analysis of pedestrian leg contacts and distribution of contact points across the vehicle front
(2015)
Determining the risk to pedestrians that are impacted by areas of the front bumper not currently regulated in type-approval testing requires an understanding of the target population and the injury risk posed by the edges of the bumper. National statistics show that approximately 10% of all accident casualties are pedestrians, with 20% to 30% of these pedestrian casualties being killed or seriously injured. However, the contact position across the front of the bumper is not recorded in national statistics and so in-depth accident databases (OTS, UK and GIDAS, Germany) were used to examine injury risk in greater detail. The results showed that some injury types and severities of injuries appear to peak around the bumper edges. Although there are sometimes inconsistencies in the data, generally there is no evidence to suggest that the edges of the bumper are less likely to be contacted or cause injury.
Autonomous Emergency Braking (AEB) systems for pedestrians have been predicted to offer substantial benefit. On this basis, consumer rating programmes, e.g. Euro NCAP, are developing rating schemes to encourage fitment of these systems. One of the questions that needs to be answered to do this fully, is to determine how the assessment of the speed reduction offered by the AEB is integrated with the current assessment of the passive safety for mitigation of pedestrian injury. Ideally, this should be done on a benefit related basis. The objective of this research was to develop a benefit based methodology for assessment of integrated pedestrian protection systems with pre-crash braking and passive safety components. A methodology has been developed which calculates the cost of pedestrian injury expected, assuming all pedestrians in the target population (i.e. pedestrians impacted by the front of a passenger car) are impacted by the car being assessed, taking into account the impact speed reduction offered by the car’s AEB (if fitted) and the passive safety protection offered by the car’s frontal structure. For rating purposes, this cost can be normalised by comparing it to the cost calculated for selected cars. The methodology uses the speed reductions measured in AEB tests to determine the speed at which each casualty in the target population will be impacted. The injury to each casualty is then calculated using the results from standard Euro NCAP pedestrian impactor tests and injury risk curves. This injury is converted into cost using ‘Harm’ type costs for the body regions tested. These costs are weighted and summed. Weighting factors were determined using accident data from Germany and GB and the results of a benefit analysis performed by the EU FP7 AsPeCSS project. This resulted in German and GB versions of the methodology. The methodology was used to assess cars with good, average and poor Euro NCAP pedestrian ratings, with and without a current AEB system fitted. It was found that the decrease in casualty injury cost achieved by fitting an AEB system was approximately equivalent to that achieved by increasing the passive safety rating from poor to average. Also, it was found that the assessment was influenced strongly by the level of head protection offered in the scuttle and windscreen area because this is where head impact occurs for a large proportion of casualties. The major limitation within the methodology is the assumption used implicitly during weighting. This is that the cost of casualty injuries to body areas, such as the thorax, not assessed by the headform and legform impactors, and other casualty injuries such as those caused by ground impact, are related linearly to the cost of casualty injuries assessed by the impactors. A methodology for assessment of integrated pedestrian protection systems was developed. This methodology is of interest to consumer rating programmes which wish to include assessment of these systems. It also raises the interesting issue if the head impact test area should be weighted to reflect better real-world benefit.
During the past five years, a Euro NCAP technical working group on pedestrian safety has been working on improving test and assessment procedures for enhanced passive pedestrian safety. After harmonizing the tools and procedures as much as possible with legislation, the work was mainly focused on the development of grid procedures for the pedestrian body regions head, upper leg with pelvis and lower leg with knee. Furthermore, the test parameters for the head and the upper leg were revised, a new lower legform impactor was introduced and the injury thresholds were adjusted or, where necessary, the injury criteria were changed. Finally, the assessment limits and colour scheme were refined, widening the range and adding two more colours in order to provide a more detailed description of the pedestrian safety performance. By abstaining from an assessment based on a worst point selection philosophy, the improved test point determination procedures that were introduced during the years 2013 and 2014 give a more homogeneous, high resolution picture of the pedestrian safety performance of the vehicle frontends. By using a uniform grid for each test zone approximately 200 test points, evenly distributed within each area, can now be assessed per vehicle. The introduction of the flexible pedestrian legform impactor in 2014 enables a more realistic injury prediction of the knee and the tibia using a biofidelic test tool. With the new upper legform test that has been launched in 2015 the assessment in that area is now focusing on the injured body region instead of the injury causing vehicle part and thus is aligned with the approach in the remaining body regions head and lower leg. At the same time, a monitoring test with the headform impactor against the bonnet leading edge is closing the possible gap between the test areas to identify injury causing vehicle parts that moved out of focus due to the introduction of the new upper legform test. The paper describes the new test and assessment procedures with their underlying philosophy and gives an outlook in terms of open issues, specifying the needs for further improvement in the future. In parallel to the work of the pedestrian subgroup, a Euro NCAP working group on heavy vehicles introduced a set of protocol changes in 2011 that were related to the assessment of M1 vehicles derived from commercial vehicles, with a gross vehicle weight between 2.5 and 3.5 tons and 8 or 9 seats. The paper also investigates the applicability of the new pedestrian test and assessment procedures to heavy vehicles.